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Biomedical subjects

G Reck

Publications and source records attributed to G Reck.

52 records · Page 3Linked to original sources
PubMed1979

Circadian rhythm of free oestradiol in relation to plasma cortisol in late human pregnancy.

The present study investigates the diurnal variations of free plasma oestradiol levels in late human pregnancy. The oestradiol levels are correlated to the maternal adrenal function as reflected by the plasma levels of cortisol. According to the half life time of oestradiol, blood samples were collected at short time intervals of 30 and 60 min, respectively. Three pregnant women volunteered in the study. Free oestradiol was measured by radioimmunoassay and cortisol was quantitated by a protein binding method. All patients exhibited a circadian rhythm for free oestradiol with significantly higher values in the early morning (28.3 +/- 7.2 ng/ml) than in the afternoon and early night (21.2 +/- 3.6 ng/ml, P less than 0.001). The course of oestradiol followed in a moderate but significant correlation plasma cortisol (r = 0.34, P less than 0.001). During the period of increasing cortisol the oestradiol levels demonstrated the phenomenon of episodic secretion. The results obtained suggest that the maternal adrenals predominantly regulate the diurnal rhythm of free oestradiol in late human pregnancy.

Circadian Rhythm↗
PubMed1979

Response of plasma non-conjugated oestradiol to manipulated adrenal function by ACTH and dexamethasone.

The present study is concerned with the regulation of free plasma oestradiol in relation to maternal adrenal function during late human pregnancy. Blood was collected in 9 patients at short time intervals of 30 min from 17 h to 3 h. In order to exclude endogenous ACTH-secretion 5 patients received 12 mg dexamethasone over 48 h. Between 20 h and 2 h 0.25 mg ACTH1-24 (Synacthen) was infused into the subjects. Non-conjugated oestradiol was determined by radioimmunoassay and total plasma cortisol by protein binding method. During the application of ACTH free oestradiol increased from 21.3 +/- 5.7 to 25.5 +/- 7.1 ng/ml (P less than 0.025) in the patients without dexamethasone. The increase was moderately correlated to rising cortisol (r = 0.58, P less than 0.001). Plasma oestradiol reached its maximum level after 90 min, followed by a tendency to decline despite persisting stimulation of maternal adrenals. The patients receiving dexamethasone exhibited during ACTH-infusion a rise of oestradiol from 3.8 +/- 1.9 to 7.8 +/- 3.1 ng/ml (P less than 0.001). Increasing oestradiol was strongly correlated to plasma cortisol (r = 0.67, P less than 0.001). The phenomenon of earlier declining oestradiol levels did not occur. These results suggest that maternal adrenals predominantly regulate the formation of free oestradiol. Plasma cortisol indicating maternal precursor production balances the increase of oestradiol by suppressing foetal precursor supply.

Adrenal Glands↗
PubMed1979

Correlation of plasma non-conjugated oestriol and plasma cortisol in late human pregnancy.

The present study concerns the diurnal variations of free plasma oestriol and their relationship to maternal plasma cortisol in late human pregnancy. Four pregnant women volunteered for the study. According to the half-life time of oestriol blood was drawn at intervals of 30 and 60 minutes, respectively, over a period of 24 hours. Free oestriol was measured by radioimmunoassay and cortisol was quantitated by a protein binding method. All patients exhibited a circadian rhythm for free oestriol with higher values in the evening and early night (14.4 +/- 3.7 ng/ml) than in the morning (11.3 +/- 2.3 ng/ml, P less than 0.001). The course of oestriol followed plasma cortisol in a significant negative correlation (r = -0.566, P less than 0.001). During the period of low cortisol concentration oestriol levels demonstrated the phenomenon of episodic secretion. The results suggest that the maternal adrenals predominantly regulate the circadian rhythm of free oestriol by a negative feed-back action on the foetal hypothalamus.

Circadian Rhythm↗
PubMed1979

[Relation between endometritis post abortum and oestrogen levels in the plasma (author's transl)].

In 13 patients with abortion in the second to fourth months of pregnancy the variation in oestrogen levels in the plasma was determined before and after abrasion of the abortus, using the radioimmunoassay method, and correlated with the results of histological examination of the abraded parts. Seven women without endometritis revealed high oestrogen concentrations before and after the abrasion (mean (1734 pg/ml or 397 pg/ml, respectively). On the fifth day after abrasion the levels corresponded with those of the proliferation phase of the normal menstrual cycle (mean 115 pg/ml). In six women with histologically established endometritis low oestrogen levels were found before and after the abrasion, the mean values being 101 pg/ml and 36 pg/ml, respectively. On the fifth day the values continued to remain low (average 25 pg/ml). The difference in oestrogen concentrations of both groups was significant and correlated well with the results of histological examination of the abraded parts.

Abortion, Spontaneous↗
PubMed1975

Control of plasma aldosterone in normal man during upright posture.

Plasma aldosterone, plasma renin activity (PRA), plasma cortisol as parameter of ACTH activity and the serum concentrations of sodium and potassium were determined at short time intervals in 10 healthy students after an overnight bedrest and during three hours of ambulation. While PRA rose significantly within 15 minutes of orthostasis in all students, plasma aldosterone showed a similar rapid increase in some of the subjects only. These persons demonstrated also a simultaneous increase of serum potassium or of plasma cortisol. Plasma aldosterone rose not before 30 to 60 minutes after change to the upright position in subjects who showed neigher plasma cortisol nor serum potassium increases. It is concluded that the immediate rise of plasma aldosterone during orthostasis seems to depend on a stimulation by ACTH of by potassium. The main stimulus of plasma aldosterone during orthostasis appears to be the renin angiotensin system. If the aldosterone response to posture is mediated only through this system a delay of 30 to 60 minutes is observed.

Adrenocorticotropic Hormone↗
PubMed1975

Effect of propranolol and prindolol on renin secretion in normal supine man.

To investigate the effect of propranolol and prindolol on renin secretion plasma renin activity (PRA) was determined overnight at short-time intervals in 10 sodium-restricted normal supine subjects. 4 of them were on a 4-days medication with propranolol, 3 were rreated with prindolol and 3 were used as control group. In normal controls renin was secreted episodically and showed characteristic night-day variations. Both in propranolol and in prindolol-treated subjects secretory episodes in renin secretion either did not occur or were less frequent than in normal controls. With one exception night-day variations in renin secretion were not observed. Mean PRA values were significantly lower than in the control group (p less than 0.001). Our results show that both propranolol and prindolol lower PRA and eliminate or reduce the frequency of secretory episodes. It is concluded that the sympathetic nervous system plays an important role in regulating night-day variations and short-time fluctuations of renin secretion in normal supine man.

Adult↗
PubMed1975

Effect of angiotensin II and of an angiotensin II analogue (Sar1-Ile8-angiotensin II) on blood pressure, plasma aldosterone and plasma renin activity in the dog.

1. The effect of infusions of equimolar doses of angiotensin II (AII) and of the angiotensin analogue Sar1-Ile8-angiotensin II on arterial blood pressure, plasma aldosterone and plasma renin activity were compared in normal anaesthetized dexamethasone suppressed dogs. 2. Angiotensin II induced a significant increase of blood pressure and of plasma aldosterone whereas plasma renin activity decreased. The blood pressure was only slightly affected by large doses of the analogue. Plasma aldosterone, however, increased and plasma renin activity decreased. These changes were significant but less pronounced than after the infusions of angiotensin II. Plasma aldosterone remained high and renin activity low for 40 min after the infusions of the analogue. 3. The results suggest a strong agonistic potency of Sar1-Ile8-angiotensin II at the adrenal and renal angiotensin receptors, and that it is almost ineffective at the vascular receptors. The inhibition of renin secretion by angiotensin seems not be related to its vasoconstrictive activity.

Aldosterone↗
PubMed1975

Severe arterial hypertension caused by chronical abuse of a topical mineralocorticoid.

A 24-year-old woman was referred to our clinic because of severe hypocalemic hypertension and latent myocardial insufficiency. Plasma renin activity and plasma aldosterone concentration were lowered. Plasma cortisol concentrations and the urinary excretion of vanillin mandelic acid were found within normal range. Some efforts to identify a specific adrenal enzymatic defect were unsuccessful. By combined therapy with spironolactone, methyldopa and clonidine, the blood pressure was significantly lowered, but not normalized. Triamterene had also an expressed hypotensive effect and induced orthostatic phenomena. After six months of hypotensive drug therapy, the patient's mother reported that her daughter consumed for more than seven years high doses of special nasal drops containing, beside ephedrine and naphazoline, the potent mineralocorticoid 9-alpha-fluoroprednisolone. A strong drug-dependence to the naphazoline component could be evaluated. The application of the mineralocorticoid was stopped, and only a slight low-sodium diet had to be added to restore the long-standing elevated blood pressure to normal

Adult↗
PubMedDate not supplied

Evidence that V+ fibronectin, GFAP and S100 beta mRNAs are increased in the hippocampus of aged rats.

In the present study, using RNA gel-blot analysis, we characterized the developmental changes in the prevalence of mRNA coding for fibronectin (FN), glial fibrillary acidic protein (GFAP), neurotrophic protein S100 beta, and beta-actin mRNA in rat hippocampus and forebrain from 1 to 720 days of age. We found that the FN and mRNA containing the V segment (FN-V) was relatively abundant at early postnatal stages, but very few transcripts were detected in adult rats. However, the hybridization signal for the juvenile FN-V mRNA was up to approximately 8-fold increased in some but not all 24-versus 6-month-old rats. Also, GFAP and S100 beta transcripts were faintly expressed at an early developmental stage, then the level of expression steadily increased starting with day 21. The greatest increase averages approximately 1.8-fold for GFAP in 24-month-old rats, and approximately 1.5-fold for S100 beta in 15-month-old versus 6-month-old rats. As all these messages are localized primarily in astrocytes, we conclude that (a) astrocyte might play an active role in aging hippocampus and (b) an increase in S100 beta and GFAP mRNA expression may precede that for FN-V mRNA expression in a hypothetical pathway of molecular events underlying neurodegeneration in the hippocampus of old rats. We also note the considerable variability among the 24-month-old rats, suggesting that aging is an individual process.

Actins↗